You want an antenna, or a GPS receiver with antenna? Not sure what
you'd need USB for, if you want just an antenna. (Most antennas with
LNAs built in power the antenna amplifier from "phantom" power on the
receiver's antenna connector.) -- If you want a USB GPS receiver for
you laptop, I'd suggest you just buy one. You should be able to find
one on ebay for around US$50, complete with built-in antenna and
magnetic base.